Circuit arrangement for discharge tubes, particularly glow discharge tubes



March 11, 1952 FALEHMANN 2,588,858

CIRCUIT ARRANGEMENT FOR DISCHARGE TUBES, PARTICULARLY GLOW DISCHARGETUBES Filed Sept. 28, 1948 5 Sheets-Sheet l vol %&%%L%

March 11, 1952 F LEI-[MANN 2 588,858

CIRCUIT ARRANGEMENT FR DISCHARGE TUBES, PARTICULARIIY GLOW DISCHARGETUBES Filed Sept. 28, 1948 v 5 Sheets-Sheet 2 6 (2 f m i I .4. 5 I? 2c73% A g i II -'ma v:

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March 11, 1952 EHMANN 2 588,858

F. L CIRCUIT ARRANGEMENT FOR DISCHARGE TUBES, PARTICULARL Y GLOWDISCHARGE TUBES Filed Sept. 28, 1948 5 Sheets-Sheet 3 Patented Mar. 11,1952 CIRCUIT ARRANGEMENT FOR DISCHARGE TUBES, PARTICULARLY GLOW DIS-CHARGE TUBES Frantisek Lehmann, Chomutov, Czechosiovakia ApplicationSeptember 28, 1948, Serial No. 51,608 In Czechoslovakia October 7, 19477 Claims.

The discharge tubes and more particularly the glow discharge tubes,which due to their low current requirements and other advantages havebeen more widely used recently, show in practical utilisation certainless favourable characteristics which are inherent to such tubes and forthe elimination of'which a number of methods have been proposed directedmore particularly to the circuit arrangement of the tubes. Thosecharacteristics of the discharge tubes towhich the proposed improvementsrelate substantially have bearing on the ignition difliculti'es, thestabilisation necessity, the flickering in each half cycle'(strob'oscopic effect) and on the unfavourable alteration of the phaseshift of the network current due to the use of choke coils.

However, the means hitherto proposed permit to eliminate usually asingle of the diflicul'ties referred to andare complicated in themselvesso that a combination of such proposed means, which sation of "theircurrent, the elimination of the strobo'scopic efiec't and a compensationof the .phase shift are obtained at the same time.

In accordance with the present invention the desired effect is achievedby connecting each of the discharge tubes to the same phase of thenetwork in series with an inductance, a capacity being connected up inparallel with at least each alternate discharge tube and with a part ofits series connected inductance adjacent to the network, while a furthercapacity is connected up in the circuit of at least onedischarge'tube'in series with the latter.

'In a circuit arrangement for two or three discharge tubesit issufficient to 'connec't'up thesaid furlther capacity only in the circuitof one of the tubes; with Tfour discharge tubes the capacity referredwill .be connected up in two circuits etc.

The aforementioned parallel capacities by means of which resonantcircuits 'for the ignition proper are obtained should be connected up inparallel with at least "each alternate discharge tube, as statedereinbeiore; of course they may be included also in the circuits of morethan each alternate discharge tube, and if desired in the circuit of allthe discharge tubes.

If the parallel ignition capacities are included only in the circuits ofsome of the discharge tubes, first those discharge tubes are ignitedwhose circuits include the said capacities and then the ignition of theother tubes takes place. For this purpose such ignition circuits arepractically quite sufficient in which the corresponding ignitionvoltages approximate more or less the resonant voltage. A particularlyadvantageous arrangement is obtained when the resonances, even partialones, in the circuits of the various discharge tubes are produced by theeffect of higher, may be different, harmonics of frequences contained inthe network current.

In the circuit arrangements of the invention relatively very smallignition condensers are quite suiiicient; this is of advantage not onlyfrom the aspect of losses and thus of economy of operation but also inview of the stability of the discharge. Indeed, too large condensersconnected up in parallel to the discharge tubes usually lead toflickermg.

In accordance with the invention, certain portions of the inductancescomiected in series with the discharge tubes may be used at the sametime in the circuits of two or more discharge tubes. As is explained inconnection with the example described in the body of the specification,a particularly advantageous arrangement is that one, in which a portionof the inductances :is made common to the circuits of at least twodischarge tubes, the said common portion being that one which isadjacent to the network.

The inductances which are connected up in the circuits of the variousdischarge tubes may be formed by a number of choke coils, preferably twochoke coils. These component chokes, if desired together with the chokesfrom the circuits of the other discharge tubes, may be assembled into astructural unit. In this connection it is of advantage to make use of acombined choke coil which preferably maybe formed of Term-- magnetic,especially iron spools as disclosed in my application Ser. No. 767,275,filed August 7, 1947, now abandoned.

Further details and possibilities of application of the circuitarrangement for discharge tubes in accordance with the present inventionare disclosed in the following description of examples in conjunctionwith the accompanying drawings inwhich Fig. '1 shows 'a circuitarrangement for two glow discharge tubes in which ignition capacitiesare connected up in both circuits and the series connected inductancesare formed each by two independent chokes;

Fig. 2 represents a similar circuit arrangement as that shown in Fig. 2,but for three glow dis charge tubes;

Fig. 3 shows a circuit arrangement for two glow discharge tubes in whicha choke is used in common for the two circuits;

Fig. l shows a similar circuit arrangement as that of Fig. 3, but forthree glow discharged tubes;

Fig. represents a circuit arrangement similar to that of Fig. 3 inwhich, however, a combined coil choke is used, and

Fig. 6 shows a similar circuit arrangement as that of Fig. 5, but forfour glow discharged tubes.

The circuit arrangements shown in Fig. 1 and likewise in Fig. 2represent, as far as the use of the individual components is concerned,one of, the.

most perfect embodiments of the invention, and accordingly theseexamples are the most suitable for explaining in detail the circuitarrangement.

In the circuit arrangement shown in Fig. 1 the terminals and 2 of asingle phase low voltage source of alternating current have connectedthereto a main ignition'circuit, which consists of a choke 3 and acondenser 4, a glow discharge tube 5 being connected to the plates ofthe condenser over a stabilising choke B. The chokes 3 and 6 formtogether the stabilisation impedance of the glow discharge tube 5, andthe ignition condenser 4 is so selected as to produce a resonant efiectwith the choke 3 preferably for any higher harmonic of the supplynetwork current. When the terminals I and 2 havebeen connected to thenetwork an increased voltage is obtained on the condenser 4 and thisvoltage leads to the ignition of the glow discharge tube 5. Inaccordance with the present invention this circuit arrangement, which issubstantially known per se, has connected in parallel the circuit ofanother glow discharge tube 1 which differs from the aforedescribedcircuit in that the stabilisation impedance in addition to the chokes 8,9 comprises a condenser l0. The values of the choke 8 and of thecondenser H in the ignition circuit are selected preferably in such away that resonance is obtained in this circuit for a different higherharmonic than in the ignition circuit of the glow discharge tube 5. V

The circuit arrangement just described secures aninstantaneousignitionof the two glow discharge tubes 5 and 1 even at a lower supply volt- 7age and without preheating the electrodes. Un-

der the influence of the condensers used the dark periods overlap eachother on the'lighting tubes so that permanently at least one of the glowdischarge tubes emits light whereby the strobes'copic effect, whichoften is very troublesome, is

eliminated in a relatively simple way. The condensers connected up inthe circuit, especially the condenser Hi, exert an influence on thepower factor of the supply network and not only can completelycompensate the harmful phase shift produced by the chokes employed, butalso when necessary they can insure an over-compensation of the saidshift.'

For the sake of completeness numerical indicai tions will be given for atypical practically tested embodiment of the above described circuitarrangement in accordance with the present invention. With standard glowdischarge tubes having an input power of 40 watts at a voltage of 220volts on the terminals i and 2, a choke 3 was used having an inductanceof 1.18 henrys and a condenser l having a capacity of l microfarad,these values corresponding to a resonance for the third harmonic of analternating current of 50 cycles/sec. Upon switching on the current fromthe network an ignition voltage of 280 volts was measured on theterminals of the condenser 4 which voltage was reduced to 105 voltsafter the ignition was completed. With a stabilising choke 5 having aninductance of 0.58 henry, a current of 0.5 ampere was obtained throughthe glow discharge tube 5 in stabilised condition and a current of 0.13ampere through the condenser 4.

. In the ignition circuit of the glow discharge tube 1 a choke 8 of 0.53henry and a condenser I l of 3 microfarads were used, which valuescorrethrough the choke 8.

The power factor of the lighting current was compensated to 0.9. It wasfound that the sum total of the capacities of the condensers used waslower than the total capacity which would be otherwise required for sucha compensation of the phase shift. w

Still better results areobtained when the circuit arrangement inaccordance with the present invention is used for three glow dischargetubes as is shown in Fig. 2. In addition to the components i to H whichare formed in the same Way and denoted by the same reference numerals asin Fig. l, the parallel by connected circuit of the glow discharge tube[2 is used and this last mentioned circuit corresponds to the circuit ofthe glow discharge tube 5.-

In connection with the numerical values of the components inthe justdescribed example, it should be noted that the values in the twocircuits of the glow discharge tubes 5 and 1 are also the same as'in thefirst example. In the ignition circuit of discharge tube l2 the sameinductance of the choke l3 was used as that of the choke 3 and thecapacity of the condenser 15 1 was 2 microfarads so that a resonance forthe discharge tube, a current of 0.136 ampere flowed through thecondenser l5 and a current of 0.45 ampere flowed through the choke l3. 7

The circuit arrangement as thus far described may be applied in similarway also for a larger number of discharge tubes. Thus, for instance,

' in a parallel connection of fourdischarge tubes it is possible tocombine two pairs of discharge tubes which are-connected up as shown inFig. 1, and by this method the combination may be -further developed fora larger number of discharge tubes. Y

The other examples shown represent simplified circuit arrangements inaccordance with the pres- V ent invention. Thus Fig. 3 shows a parallelconnection of two glow discharge tubes 5 and 1, the

tissues-a circuit of the-glow discharge tubeb being quite similar to thearrangement of Fig. 1, while the second glow discharge tube "IIisconnected over *portions of its stabilisin'g circuit directly to theterminal I of the network, andis connected to the terminal 2 ofthentwork behind the choke 3. The supply con ductors of the glowdischarge tube 1 include the chokes 8 and!) corresponding to the chokes3 and 6,'the equalising condenser being connected up between the choke 9and the network. The ignition condenser l l is connected in parallelwith the glow "discharge tube 1-to the choke 9 and condenser 'lll'andconsti- "tutes the ignition circuitwith the chokes '3 and 8..An'advantageof this arrangement consistsmore particularlyi'n'theSimultaneous utilisation of the choke 3 for'the series circuits of bothglow discharge tubes and 1 whereby the material for "theotherwise'neees'sary second choke is saved and this single "choke '3"view of the predominantlyind'uctive load in the circuit "or the'glowdischarge tube 5 and the capacitive loa'd'in the 'circuitof theglow discharge "tube 1, the totalworking current flowing through thechoke 3 is extraordinarily small because the a 'just me'ntionedcurrentsneutralise each other in maybe very small sincejin the choke. Moreover,in viewof the fact that in the ignition circuitof the glow dischargetube 1 the two chokes 3 and 8 are in series and therefore theirinductancesare added to each other,a frelatively'small condenser H issufiicient for an appropriate increase in the ignition voltage.

As it has been stated hereinbefore usually it is not necessary inthese'casesthat a complete resonance should beobtained in theignitioncircults, it being sufl'icient to obtain-a voltage lower :thantheresonant voltage in order toimpress 'on the terminals of the tube atleasttheignition voltage. This remark'applies to both the last mentionedignitioncircuits, i.-e.for the circuits includingthe condenser I l andthe condenser 4.

4 Another advantage of the aforedescribed sim- "IpIified arrangementconsists in the possibilityof "o'jmitting the ignition condenser 4 inthe circuit ofthegl'ow discharge tube 5. For thisreasonthe condenser 4is shown in dottedlines in'Fig.'3. In

this case ffirst the glow discharge tube 1 is ignited under the effectof the ignition circuit 'when the voltage has 'beenconnected to theterminals l and 2, and thereafter also the glow 'discharge'tube 5 isignited due tothe e'fiectof the voltage-increased by the voltage'dropacross the choke 3 enem be alsoacross the choke 6.

The practically "tested values for thevarious components in the abovedescribed examples are 'thefollowing The choke 3 havingan inductance of1.2.henr'ys, the choke 6 has an inductance of '0:5 henrya-nd thecondenser 4 a capacity of 0.5 micr'ofarad;

"the'chok'e -8 has an inductance of 1.2henrys, the

sun directly to "the network terminals 1 and 2 The corresponding valuesof the components of this circuit may be I the following: 7,

The choke may have an inductance of 1.2

6 ihenr'ysjthe choke M an inductance of 0.25 henr-y andthe condenser I5a capacityof 3 'micro'farads.

All the chokes included in the circuit arrangements as far described, orsome of them, may be conveniently and easily formed into a structuralunit by connecting the cir'cuits of the'various chokes to a commonmagnetic circuit.

In the usual so-called core construction of chokes, the cores of acommon magnetic frame carry either the corresponding individual chokesor their separate coils, the magnetic frame being closed by means of endyokes. In the caseof a circuit arrangement with more than two glowdischarge tubes the two magnet cores may be conveniently connectedalsoby means of amiddle yoke.

The construction of such a choke is shown diagrammatically in Fig. 5,,in which the oncuitarrangement corresponds fully to that of Fig. 3andtherefore the individual components are denoted by the same referencenumerals. The combined choke is assembled in this case of separatecomponent chokes 3, 6, 8 and 9 and ic'ompose'd of windings iii which arewound spirally, e. g. of an insulated iron strip. The various windingsare assembled in two columns which are connected at each end by means ofyoke l1 and I8, respectively.

The/choke construction shown in Fig. 5 is very advantageous especially"in respect of econemy of the material for making the chokes and also inrespect of the advantageous mutual magnetic coupling 'of the variousparts of the circuit during operation. In this way diilerentirregularities may be equalised, and if one of the glow discharge tubesbecomes extinguished for any reason it is immediately ignited again. Inthis embodiment of the invention it is possible precisely to omit oneignition circuit for one of the glow discharge tubes, that is to omitthe condenser 4, whereby the voltage drop across the component choke 3and that across the component choke has well, are added to the supplyvoltage on the terminals I and 2 and thus produce an increased ignitionvoltcausing the glow discharge tube 5, which does not yet'glow or hasbeen just extinguished, to be struck when the other discharge tube has"been previously ignited. The embodiment of the combined choke justdescribed may used with advantage in a similarway for three parallellyconnected glow di charge tubes in an arrangement corresponding tothatshown in Fig. 4. The common choke -may conveniently provided with ayoke in acentraliposition. v

In this connection Fig. '6 "shows diagra nniati Cally the use of acommon choke for feeding in parallel .four glow discharge tubes 5, 1, 2iand 22 ffrom a single phase network I, 2. The lower part of this figureshows a pair of glow discharge tubes i with accessories, which paircorresponds to Fig. 5. In addition thereto second pair of glow dischargetubes 2! and 2 is rovided which may be connected up togethe h theirrespective circuit elements to form igement quite similar to that of thefirst'pa-ir 5 l, "and it of advantage to chose the the elements as tosecure in the ignition circuit an increase the t'oltage under the effectof iffei ht harmonics. its upper part a .figw a. ehews s mewhat .I liedcircuit arrangement for the second pal-r ef glow discharge tubes 2| and22.

a The component chokes -23 and 24 correspond quiet and continuousburning of the discharge tubes is not an absolutely necessary require-'ment.

"The effect of the condensers 26, 2'! and 28 is quite the same as thatof the condensers s, H] and H of the lower pair of glow discharge tubes5 and '4. Similarly as in the foregoing circuit arrangement, thecondensers ti and 26, shown in dotted lines, may be omitted, and thenall the four glow discharge tubes will be struck by the ignitioncircuits containing the condensers II and Ed. The condensers IE] and 21serve for compensation and their operation has been explainedin theforegoing description.

Fig. Gshows the end yokes, l1 and it, which correspond to the yokesdenoted by the same references in Fig. 5, and a middle yoke 29, theconstruction of which is adapted to its function. The use of such amiddle yoke represents a relatively great saving of material as comparedwith the use of two independent chokes corresponding to a separatefeeding of the two pairs of glow discharge tubes, the pair Eand on theone hand, and the pair 2i and 22 on the other hand. The middle yoke 29may be made weaker than the edge yokes I1 and I8.

Referring now to the values of the circuit elements in the arrangementshown in Fig. 6 each pair of windings of the lower half of the chokeshas a self inductance of 0.2 henry and the corresponding condenser d hasa capacity of 3 microfarads, the condenser is has a capacity of 4microfarads and the condenser H has a capacity of 3 microfarads. In theupper half of the chokes each pair of windings has a self inductance of0.3 henry, and the corresponding condenser 26 has a capacity of 2microfarads, the condenser 2'1 has a capacity of 4 microfarads and thecondenser 23 has a capacity of 3 microfarads. Of course, as it has beenstated in the foregoing description, the condenser 1i, and if desiredalso the condenser 26, may be omitted.

By the use in accordance with the present invention of combined chokesassembled of component chokes, first of all a large amount of materialis saved, as previously stated, which material would be requiredotherwise for the construction of the individual chokes separately fromoneanother. A further advantage in the present case consists in theprovision of a common magnetic coupling for all the component chokes,such a coupling having a favourable effect on the compensation of anyirregularities which may appear during the operation of the glowdischarge tubes.

The advantage of using ferro-magnetic windings for the combined chokesappears from the a part of the description relative to Figs. 5 and 6 ofthe drawings. Apart from the possibility of substituting ordinary ironfor the more valuable copper, an exceedingly simple construction,

which is very advantageous from the standpoint of manufacture and ismuch superior to the constructions as hitherto used, is secured for suchchokes. Another important advantage consists in the possibility ofobtaining combined chokes which have distinct electrical characteristicsof any desired value, by assembling identical windings manufactured inmass production.

The examples described do not exhaust all the possibilities ofutilisation of the invention. Still further possibilities existconsisting in various combinations of the elements referred to in thepresent specification.

What I claim is:

1. In combination with a single phase source of alternating current of apredetermined frequency, a circuit arrangement for starting and feedingfirst and second glow discharge tubes connected to said source viaparallel circuits, the

circuit to each tube from said source including a starting inductanceand a stabilizing inductance connected in series with the tube and acapacity connected in parallel with the tube through only one of saidinductances, and one only of said tube circuits including a capacityconnected in series with the tube to establish a phase differencebetween the current waves of the two tube circuits, the values of thestarting inductance and parallelconnected capacity of each tube circuitbeing so chosen as to produce respectively therein substantiallyresonant conditions at different harmonics of the frequency of saidsource.

2. A circuit arrangement for a pair of glow discharge tubes as definedin claim 1 wherein the inductance capacity starting units of the twotube circuits become substantially resonant respectively at the secondand third harmonics of the frequency of said alternating current source.

3. In combination with a single phase source of alternating current of apredetermined frequency, a circuit arrangement for starting and feedingfirst and second glow discharge tubes connected to said source viaparallel circuits, the circuit to said first tube from said sourceincluding a starting inductance and a stabilizing inductance connectedin series with the tube, and the circuit to said second tube from saidsource including a starting inductance and a stabilizing inductance andalso the starting inductance only included in said first tube circuitconnected in series with the second tube, and a capacity connected inparallel with the second tube through only one of the said inductancesseries connected with said second tube, the capacity and startinginductances in the circuit of said second tube having such a value as toestablish in said circuit a substantially resonant condition, and oneonly of said tube circuits also including a second capacity connected inseries with the tube to establish a phase difference between the currentwaves of the two tube circuits. 7

4. A circuit arrangement for a pair of glow discharge tubes as definedin claim 3 wherein the circuit of said first tube includes only saidstarting and stabilizing inductances.

5. A circuit arrangement for a pair of glow discharge tubes as definedin claim 3 wherein all the said inductances are constituted respectivelyby windings distributed on two columns of a common choke, the windingappertaining to the starting inductance in the circuit of said firsttube being arranged on one of said columns, and the three windingsappertaining respectively to the remaining three inductances arearranged on the other of said columns. 7

6. An arrangement for two pairs of glow discharge tube circuits with thetube circuits of each pair arranged in accordance with claim 3 whereinall of the said inductances of the four lamp circuits are constitutedrespectively by windings distributed on two columns of a common choke,the ends of said columns being magnetically connected by end yokes andtheir mid-parts bein magnetically connected by a middle yoke, the twowindings appertaining respectively to the starting inductances in thesaid first tube circuit of each pair being arranged on one of saidcolumns at opposite sides of said middle yoke, and the three windingsappertaining respectively to the remaining three inductances in the tubecircuits of each pair being arranged on the other of said columns atopposite sides of said middle yoke.

7 A circuit arrangement for two pairs of glow FRANTISEK LEHMANN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 15 2,195,114 McCarthy Mar. 26,1940 2,373,402 Lecorguillier Apr. 10, 1945 2,404,254 Short July 16, 1946

